Fermi-Edge Singularity with Backscattering in the Luttinger-Liquid Model

We study the response of the interacting electron gas in one dimension on the local external potential. In the low frequency limit the power-law singularities are essentially modifyed by backscattering effects which, in the case of zero forward scattering, result in the universal critical exponent depending only on the Luttinger-liquid interactions. The results obtained may be used to describe singular responses of the 1D boson chains.Comment: 11 pages in LaTex, UBCTP-NP-93-00

Supercurrent Stability in a Quasi-1D Weakly Interacting Bose Gas

We discuss a possibility of observing superfluid phenomena in a quasi-1D weakly interacting Bose gas at finite temperatures. The weakness of interaction in combination with generic properties of 1D liquids can result in a situation when relaxational time of supercurrent is essentially larger than the time of experimental observation, and the behavior of the system is indistinguishable from that of a genuine superfluid.Comment: Revtex, 4 pages, no figures; Submitted to Phys. Rev. A (Brief Reports

Criticality in Trapped Atomic Systems

We discuss generic limits posed by the trap in atomic systems on the accurate determination of critical parameters for second-order phase transitions, from which we deduce optimal protocols to extract them. We show that under current experimental conditions the in-situ density profiles are barely suitable for an accurate study of critical points in the strongly correlated regime. Contrary to recent claims, the proper analysis of time-of-fight images yields critical parameters accurately.Comment: 4 pages, 3 figures; added reference

Comment on ``One-Dimensional Disordered Bosonic Hubbard Model: A Density-Matrix Renormalization Group Study"

We present the phase diagram of the system obtained by continuous-time worldline Monte Carlo simulations, and demonstrate that the actual phase diagram is in sharp contrast with that found in Phys. Rev. Lett., 76 (1996) 2937.Comment: 1 page, LaTex, 1 figur